git_cl_hooks: get cl fields vi git_cl accessors instead of using backquote

git_cl_hooks.py

Index: git_cl_hooks.py
diff --git a/git_cl_hooks.py b/git_cl_hooks.py
index 059f52e26c6a79f14ba8c05e1df5cb6f70cb8935..4202502c6e53d61a82292d7de6d3a231a8770d1a 100644
--- a/git_cl_hooks.py
+++ b/git_cl_hooks.py
@@ -9,10 +9,16 @@ import sys
 
 import breakpad
 
+from git_cl_repo import git_cl
+from git_cl_repo import upload
+
 import presubmit_support
 import scm
 import watchlists
 
+# Really ugly hack to quiet upload.py
+upload.verbosity = 0
+
 def Backquote(cmd, cwd=None):
   """Like running `cmd` in a shell script."""
   return subprocess.Popen(cmd,
@@ -43,10 +49,11 @@ class ChangeOptions:
     # We use the sha1 of HEAD as a name of this change.
     name = Backquote(['git', 'rev-parse', 'HEAD'])
     files = scm.GIT.CaptureStatus([root], upstream_branch)
-    issue = BackquoteAsInteger(['git', 'cl', 'status', '--field=id'])
-    patchset = BackquoteAsInteger(['git', 'cl', 'status', '--field=patch'])
+    cl = git_cl.Changelist()
+    issue = cl.GetIssue()
+    patchset = cl.GetPatchset()
     if issue:
-      description = Backquote(['git', 'cl', 'status', '--field=desc'])
+      description = cl.GetDescription()
     else:
       # If the change was never uploaded, use the log messages of all commits
       # up to the branch point, as git cl upload will prefill the description